ID Please?

[bearjohnson]

Does anyone know what this little guy is? Smack in the middle of the picture at the base of the acro. It looks kinda like a star with short nubs and I believe it has a hard shell.

Good, Bad, Keep or Ditch?

 

[Sdoutreefer]

Looks like a snail shell.. does it move? See if you can pull it off the rock.

 

[NanaReefer]

Spiny Star Astraea Snail. http://www.101-saltwater-aquarium.com/others-care-information/spiny-star-astraea-snail.php